Pema Chodron (2007). “Always Maintain a Joyful Mind: And Other Lojong Teachings on Awakening Compassion and Fearlessness”, p.85, Shambhala Publications
Wayne W. Dyer (2009). “The Invisible Force: 365 Ways to Apply the Power of Intention to Your Life: Easyread Super Large 20pt Edition”, p.274, ReadHowYouWant.com